In certain forms of robot machine tools, there is a rotating or reciprocating mandrel portion of the tool upon one end of which is attached a tool for working or shaping materials under manufacture. In order to provide power or to control the tool, a means for signalling changes of location, angle, and other required modes is required. A power and/or a signal cable may be used to connect the tool to the remainder of the machine.
In the case of a tool attached to the end of a reciprocating mandrel, a convenient means of connection can be a cable spiralled around the reciprocating mandrel from the stationary bulk of the machine to the tool mounted on the mandrel. In operation, the coil of cable spiralled around the mandrel lengthens and shortens in one axis as the tool to which it is attached reciprocates back and forth performing its work. In another axis, the coils of cable may collapse on each other around the reciprocating mandrel to cause wear of the cable moving against its own coils or the mandrel as the mandrel continuously reciprocates within the coil of cable.
Increasing the stiffness of the cable to prevent such collapse of the coil of cable does not always solve the problem of wear, in that a very stiff cable may be difficult to bend into a spiral coil of appropriate size around the mandrel and may be too stiff to flex properly around the mandrel as the mandrel reciprocates and the cable coils lengthen and shorten with the movement of the tool head on the mandrel.
The invention provides an alternate means of support and strain relief for a coil of cable positioned around a reciprocating mandrel.